The submarine is now undergoing tests in Scotland. LONDON, England (CNN) -- Eleven sailors were permitted to leave a British nuclear submarine after expressing fears over its safety, the Ministry of Defense has confirmed.

Crewman on H.M.S. Trafalgar raised concerns with their commanding officer who felt "the most prudent action was to land them and replace them," according an MoD spokesman.

The spokesman "categorically denied" any suggestions of a "mutiny" on board, and said that no individuals refused to sail on the submarine.

"A number of allegations were made concerning systems defects on the submarine -- all of which have been examined, the majority of which have been unfounded and none of which had any serious safety implications," he said.

He added, "The Royal Navy would never send a submarine to sea unless it was totally confident it was safe to do so."

The Daily Mirror newspaper said the sailors were worried about up to 270 defects that undermined the safety of the submarine, including a faulty nuclear reactor, sub-standard escape, safety and emergency equipment and oil contamination in the water supplies.

The incident took place before the submarine was due to begin tests following minor repairs at the Faslane nuclear base in Scotland.

H.M.S. Trafalgar has been out of service since it ran aground off the Isle of Skye in November 2002. Three sailors were injured in the incident which caused just under a million-dollars worth of damage.

A temporary replacement crew joined the other 109 members after the 11 men spoke out about their safety concerns last Friday to commanding officer Mark Williams.

The MoD said a number of system defects had been identified but all had been checked and passed fit before sailing from Devonport dockyard, where the sub had undergone 15 months of major repairs.

The MoD said no disciplinary measures are currently being considered against the 11 men.

The Trafalgar now continues its "shake-down" in Scotland in which testing of the vessel and training of the crew continues in preparation for deployment.

"Neither the commanding officer or the Navy Nuclear Safety Authority has expressed concerns. They are totally confident in the safety of the submarines", the MoD said.